Re: [9fans] Client/server program sample code request..

[Dennis Ritchie <dmr@bell-labs.com>]

presotto@plan9.bell-labs.com wrote (I snip a lot):
> 
> Dial is actually from research Unix.  Wnj and Sam Leffler were doing
> the socket stuff while I was at UCB.  It was not bad considering
> they were starting from scratch and other interfaces were just
> as awkward...

> When I came to the labs, research Unix was using the Datakit
> network instead of ethers and IP (we bell heads spent a long
> time denegrating ethernets and IP before were beaten into
> submission but that's another story).  Datakit
> used relative hierarcical string addresses (things like
> "mh/astro/r70").  They already were using a dkdial() call
> that looks pretty much like the dial() in Plan 9.  The interface
> for datakit was file system based, also very much like the Plan 9
> one is now.  When rtm ported the 4.1c BSD IP code into research Unix,
> we adopted the datakit model rather than sockets because it was,
> we thought, easier to deal with.
> 
> The Plan 9 interface is just a continuation along the same lines.

In case you don't recognize the "rtm"-- for historical completeness,
it is Robert Tappan Morris.

The roots of the approach are clearly exposed in
 http://cm.bell-labs.com/cm/cs/who/dmr/ipcpaper.html
by Dave and me.  He did more of the work, as usual.
The underlying ideas go back a long way.

> 
> Thank Lee McMahon, Sandy Fraser, and Greg Chesson for the nicer
> model that came with the Datakit.  We just recognized the elegance
> of their work and expanded it.

Indeed.  From the application level, the main difference between the
original UCB socket approach and the one that grew in the Plan 9 scheme
is that network names should be textual and visibly hierarchical,
and translated into raw network addresses by a mechanism that isn't written
or compiled into every program that uses them.  Sort of like DNS.  Also,
that I/O over a network connection should be made to look like other I/O
to the extent possible.   Dealing with two network technologies simultaneously
(Datakit vs. Ethernet->Internet + TCP/IP) helped push the generalization.

	Dennis